At the deposition of the pollen grain upon the stigma is followed by a process true germination was established by Van Tieghem as long ago as 1871, who in printed out the similarity of its behaviour to that of the spores of Lycopodiaceæ and many ferns, and indicated that the pollen tube may be compared to the prothallium proeeding therefrom, especially in the cases of those prothalli which contain no lorophyll. Its growth is prepared for by the deposition in the grain of several ms of reserve material, chiefly of carbohydrate nature. During the process of determination these reserve materials have been found to change, indicating an active metabolism, while at the same time active respiration goes on, as shown later by angin. Not only do we find reserve materials deposited in the pollen grain, but rther, we can identify a similar store in the tissues of the style, especially when that began is a long one, and the pollen tube has consequently some distance to travel before reaching the ovules. In most cases of the storage of reserve materials in plants we find evidence of the utilization of such stores by the presence and activity of enzymes, Thus in seeds, orup-Besanez, Guignard, Brown and Morris,|| and others, have proved their presence; in tubers, Baranetzki found them in the potato; in leaves, Brown and Morris, and Yines have demonstrated their existence, and their relation to the temporary deposits of starch in the chlorophyll grains. The writer; has shown various enzymes to exist in seeds and tubers, transforming for the nutrition of the plant, proteids, fats, and carbohydrates.